Lamp socket



2 SHEETSSHEET 1 INVENTOR. Hn/e/ey C. ROBE/9750M H. c. ROBERTSCN LAMP SOCKET Nam 27, 1 .9531

Filed Dec. 2, 1947 H. C. ROBERTSON LAMP SOCKET 2 SHEETS-SHEET 2 Filed Dec. 2, 1947 JNVENTOR.

HQQQ'Y C. ROBERTSON BY wafiww Patented Nov. 27, 1951 UNITED STATES PATENT OFFICE Claims.

This invention is a lamp socket of the type gdiagted to receive the usual incandescent lamp Conventional lamp sockets comprise an outer shell provided with an insulating liner within which is positioned a core consisting of a screw shell to receive the threaded base of the lamp and a core body in which a switch mechanism is housed. This core body has heretofore generally been made from porcelain or an organic plastic, molded into the desired shape with passages and openings to receive the switch mechanism, lamp terminal screws and the center contact with which the corresponding contact or" the lamp is engaged when the lamp is screwed into.

the threaded shell.

The core body of porcelain or plastic constitutes an appreciable part in the cost of manufacturing lamp sockets and is not infrequently the first element of the structure to become broken. This is particularly true with sockets having porcelain core bodies for, if such a socket is dropped or the screws or bolts which attach the body to the threaded shell are fastened too tightly, the friable porcelain will be broken and the socket rendered unsafe for use.

The object of the present invention is to provide a lamp socket, and more particularly the core of such a socket, wherein the use of plastics or porcelain in the formation of the core body is eliminated and there is substituted therefor a fabricated body made of tough and strong sheet insulating material adapted to be readily formed by folding a flat blank of such material.

In the preferred form of the present invention, the core of the body is stamped from sheet material, such as vulcanized fibre, and thereafter scored and bent into a shape to be received within the outer shell and liner. The switch mechanism, lamp terminals and center contact are all mounted within or on the sheet material of the folded blank and the electrical wire terminals of the core serve to hold the blank in folded relation and also serve to attach this corebody to the threaded shell of the socket. A socket thus fabricated is economical to manufacture and is practically unbreakable. It is also absolutely safe from the standpoint of electrical hazards, such as fire, short circuits or electrical shocks to the user.

Features of the invention, other than those adverted to, will be apparent from the hereinafter detailed description and appended claims, when read in conjunction with the accompanying drawings.

(Cl. EMF-51.17)

The accompanying drawings illustrate one practical embodiment of the invention, but the construction therein shown is to be understood as illustrative, only, and not as defining the limits of the invention.

Figure 1 shows a lamp socket embodying the present invention with the core of the socket in elevation and the outer shell and liner in section.

Figure 2 is a perspective view of the core removed from the shell and liner with the screw shell in the core shown in phantom, so as not to obscure the core body and associated electrically conductive parts.

Figure 3 shows a face view of the blank from which the core body is formed.

Figure 4 is a perspective view showing the fabricated core body from which are detached the several operating parts associated therewith. The light straight lead lines indicate the cooperative relation of the different parts of the structure shown in this figure.

In the manufacture of a plug core in accord ance with this invention, a blank, such as shown in Figure 3, is first stamped from vulcanized fibre or some other appropriate bendable insulating sheet material. This blank is provided with scored lines I which divide the different portions of the blank into a plurality of wall portions. The central portion 2 of the blank is substantially circular and is adapted to form the top wall of the core body. The portions 3 and 4 are rectangular, adjoint the opposite sides of the top wall 2 and are adapted to form two opposite side walls of the body, while the portions 5, 6, l and 8 are in the nature of Wings or flaps adapted to be folded over one another to collectively form the other two side walls of the body.

The folding of the core may be conveniently accomplished with an appropriate jig or mandrel, whereby the walls 3 and 4 are folded downwardly into perpendicular relation to the top wall 2 and the flaps 5 to 8, inclusive, are folded along the scored lines so that the flap 5 overlaps the flap 6 in facial contact therewith, while the flap overlies the flap 8 in a like manner, to produce the substantially rectangular core body 9 shown in Figures 2 and 4. The side walls of this core body form a substantially rectangular tubular structure, open at its bottom and closed at its top by the top wall 2.

Prior to the folding of the blank as described, said blank is perforated to provide therein properly spaced and disposed openings by which the metal adjuncts or accessories of the core may be anchored thereto. More specifically, the flaps to 8 inclusive have formed therein perforations H], the wall 4 is provided with an elongated slot I! and perforations l2, and the top wall 2 is provided with perforations l3, i i and i5.

When the blank is folded, the perforations ll] of the flap 5 register with perforations It] in the flap 5 and similarly corresponding perforations of the flap l register with those of the flap 8, so as to permit the flaps to be permanently secured in facial relation by terminal clips l6 and I1. These terminal clips are stamped up from sheet metal of resilient character, such, for example, as brass or Phosphor bronze. Figure 4 very clearly shows their construction. Both of these clips are the same. The strip material from which the clips are formed is bent upon itself to produce a resilient end portion 18 integral with which is formed a pair of bendable tongues I9, extending in parallel relation to one another. The arm 20 of the clip is resilient and has therein an opening 2! through which projects a keeper 22 formed integral with the other arm of the clip. The bared end of a wire is adapted to be passed through the keeper 22 when the arm 29 of the clip is forced in the direction of its other arm, so that, when released, the resilient clip will grip the bared end of this wire. The free end of the wire may be passed through an opening 23 to rest in the notched end 24 of the arm 20. The upper portion of the clip is formed with upstanding parallel offset tongues 25.

After the blank has been folded as described, the tongues E9 of the clips are adapted to be passed through the registering perforations IQ of the wide wall flaps and bent flat to anchor the clip to these side walls and also hold the flaps of the latter in overlapped relation. Likewise the tongues 25 are passed upwardly through perforations 13 in the top wall 2 and project above grounded side of the socket and consequently the tongues 25 thereof may simply be passed through the registering perforations in the flange 21 and bent flat to permanently anchor the shell 26 to the body 9. This establishes electrical contact between the shell 25 and the clip.

The clip 56, however, is adapted to be connected to the center contact of thesocket and consequently must be insulated from the shell 26. This may be accomplished by forming in the flange 21 of said shell an opening and mounting in said opening an insulating fibre filler 28 provided with perforations [3a through which the tongues 25 are adapted to paSS in insulated relation to the shell. The filler 28 is shown in Figure 4 as having a reduced under portion 29 adapted to fill in the enlarged hole of the flange 27, while the upper portion of the part 28 is broadened out to rest upon the flange 21, so that when the tongues 25 are bent over the upper surface of the part 28, they will bind the shell 26 firmly to the core body El. The filler 28 may be formed of two laminated sections if desired.

The tongues 25 are also availed of; in the construction shown, to anchor a switch plate 3i] to the under side of the top wall 2 of the body. This switch plate 38 is of resilient metal, such as brass or Phosphor bronze and it is provided with perforations 3! which correspond to and are adapted to register with perforations 13, so that, when the plate Si) is positioned against the under side of the top wall 2 and the tongues 25 passed therethrough and bent over as described, the switch plate will be firmly secured in position.

The greater portion of the length of the switch plate 38 projects freely toward the center of the wall 2 in a manner to be free for flexing resiliently and its free end is provided with a camming surface 32, shaped for cooperation with a camming portion 33 formed on a switch arm 34. This switch arm is secured to a plate 35 which forms the center contact with the socket. The switch arm is positioned below the wall 2, while the contact 35 is positioned above said wall, but a pivot pin 36 passes through both parts and through the perforation [5 of the top wall and mounts the switch arm 3G for pivotal movement on this pin. The center contact 35 is firmly anchored in place in facial relation to the top surface of the wall 2 by-bendable tongues 3'! which pass through the perforations M in the top wall and are bent flat on the under side thereof to clamp the contact 35 firmly in place. The switch arm 34 extends from the pivot 36 to an integral camming portion 33 and is then bent abruptedly downward, as shown at 38, and then laterally, at 39, to project through the slot ii. in the wall 4 of the core body, as shown best in Figure 2. The free end of the switch arm is serrated and bifurcated at 4B and its end is adapted to be forced into the shank of a finger piece il, positioned exteriory of the slot and projecting into convenient position for operation exteriorly of the outer shell of the plug.

To energize or de-energize the lamp, the finger piece 45 is grasped and the switch arm 34 shifted about the axis of the pivot 36, to move the camming portion 33 of said arm into and out of engagement with the camming portion 32 of the switch lever 39. This latter camming portion is so shaped as to lock these parts together against inadvertent displacement of the switch arm from their mutual contact, but the resiliency of the spring plate 559 permits the withdrawal of the switch arm when it is desired to de-energize a lamp associated with the socket.

The switch arm may be locked. in off position by engagement thereof with a retaining plate 42. This plate is very similar to the plate 30 and it is shown in detail in Figure 4. It has tongues 43 adapted to be passed through the perforations I 2 of the wall 4 and bent flat. They position the retaining plate so that its free end 44 may be engaged by the portion 38 of the switch arm and said plate is provided with a camming surface to lock the arm against inadvertent disengagement from the retaining plate.

The core is adapted to be received within a liner positioned within an outer shell 45, the rear end of which is closed by a cap 45. The outer shell, liner 48 and the cap are conventional except that the shell and liner are each provided with a slot ll appropriate to give clearance for operation of the finger piece ll when the parts are assembled and to also allow of removal of the outer shell and liner. Fig. 1 shows the assembly and illustrates the manner in which the wires 0 and c of the feed cable C are connected to the terminals of the socket core.

From the foregoing description of the structure, it will be apparent that current fed through the wire 0, passes through clip l6 and switch plate 30 through the switch arm 34 to the center contact 35 and, after passing through the filament of the lamp, returns through theshell of the bulb to the inner shell 26 electrically connected to the clip ll, tto which the electrical llead c is connected.

The lamp core of this invention may be manufactured at a fraction of the cost of sockets embodying a solid core body of porcelain or plastic material. The parts may be assembled with ease and expedition and without requiring separate fastening screws, bolts or other adjuncts commonly employed in conventional sockets. The finished socket is electrically absolutely safe. There is no chance of breakage under ordinary use and no chance of short circuiting or electrical shocks to the user.

The foregoing detailed description sets forth the invention in its preferred practical form, but the invention is to be understood as fully commensurate with the appended claims.

Havin thus fully described the invention, what I claim as new and desire to secure by Letters Patent is:

1. A lamp socket part comprising: a core body of sheet insulating material having a wall at one end and having four side walls integral with the end wall, two of said side walls having overlapping portions with alined perforations therein, and electrical terminal connections embodying clips provided with tongues passed through said perforations to maintain said overlapping portions in overlapped relation.

2. A lamp socket part comprising: a core body of sheet insulating material having a wall at one end and having four side walls integral with the end wall, two of said side walls having overlapping portions with alined perforations therein, and electrical terminal connections embodying clips provided with tongues passed through said perforations to maintain said overlapping portions in overlapped relation in combination with a threaded inner shell having a perforated internal flange, and additional tongues on the terminal clips extending through the perforations in said flange and bent over to secure said shell to the core body.

3. A lamp socket part comprising: a core body of sheet insulating material having a wall at one end and having four side walls integral with the end wall, two of said side walls having overlappin portions with alined perforations therein, and electrical terminal connections embodying clips provided with tongues passed through said perforations to maintain said overlapping portions in overlapped relation, in combination with a threaded inner shell having a perforated internal flange, additional tongues on the terminal clips extending through the perforations in said flange and bent over to secure said shell to the core body, a center contact mounted on the core body within the shell, a current carrying plate having perforations through which tongues on one of the terminal clips extend, and a switch arm pivoted to the center contact and manually movable into and out of contact with said current carrying plate.

4. A lamp socket part comprising: a core body of sheet insulating material having a wall at one end and having four side walls integral with the end wall, two of said side walls having overlapping portions with alined perforations therein, and electrical terminal connections embodyin clips provided with tongues passed through said perforations to maintain said overlapping portions in overlapped relation, in combination with a threaded inner shell having a perforated internal flange, additional tongues on the terminal clips extending through the perforations in said flange and bent over to secure said shell to the core body, a center contact mounted on the core body within the shell, a current carrying plate having perforations through which tongues on one of the terminal clips extend, a switch arm pivoted to the center contact and manually movable into and out of contact with said current carrying plate, and a retaining member detachably engaging with the switch arm when the latter is in off position.

5. A lamp socket part comprising: a core body of sheet insulating material having a wall at one end and having four side walls integral with the end wall, and current carrying terminals penetrating overlapping portions of the side walls to secure them in overlapped condition.

HARRY C. ROBERTSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 57,024 Wheat et al. Aug. 7, 1866 132,075 Heyl Oct. 8, 1872 316,003 Brangs Apr. 21, 1885 418,426 Thone Dec. 31, 1889 1,251,739 Benjamin Jan. 1, 1918 1,262,237 Nelson Apr. 9, 1918 1,478,701 Diehl Dec. 25, 1923 1,507,086 Orpen Sept. 2, 1924 1,824,231 Popp Sept. 22, 1931 2,405,034 Harford July 30, 1946 2,408,843 Gauthier Oct. 8, 1946 2,436,756 Larkin Feb. 24, 1948 

